The present invention relates, in general, to a highly versatile, automated system for processing blood, blood components, and other fluids included in such processing. More particularly, the present invention relates to an automated system that can separate blood into two or more blood components (xe2x80x9capheresisxe2x80x9d), and then perform a further procedure involving one or more of the separated components.
The term xe2x80x9capheresisxe2x80x9d means removing whole blood from a patient or donor and separating the blood into two or more components. A separated component can be collected from a healthy donor, and later transfused to a patient in need of the component. Apheresis is also used in therapeutic applications to treat illness by removing diseased or otherwise undesirable components from a patient.
In a basic apheresis procedure, blood is withdrawn from a donor through a needle inserted into the vein of a donor. The needle is attached to one end of a plastic tube which provides a flow path for the blood. The other end of the tube terminates in a container for collecting the blood. The collected blood is then separated in a separator, such as a centrifuge, into its components. The desired blood component which, depending on the procedure, can be red blood cells, platelets, plasma, white blood cells or stem cells may be collected and stored for later transfusion to a patient in need of the blood component.
More recently, xe2x80x9cautomatedxe2x80x9d apheresis systems have come into widespread use. These automated systems utilize disposable, pre-sterilized fluid circuits (i.e., tubing sets) through which the blood flows. The fluid circuits are mounted on re-usable hardware devices or modules that have pumps, valves, sensors and the like. These automated systems further include an internal computer and associated software programs (controller) which control many of the processing functions.
For example, in an automated system, blood flow through the fluid circuit, the operation of valves and pumps, may be monitored and regulated by the system. An automated system can be programmed to initiate, terminate or otherwise control certain functions based on patient or donor data (e.g., height, weight, sex, hematocrit). Likewise, an automated system may monitor certain functions with the aid of sensors which can, for example, sense the amount of the collected or withdrawn component. Optical sensors are used to measure the clarity or content of a fluid, or sense the presence or absence of certain components.
Automated apheresis systems are available from several different manufacturers. Examples of commercially available apheresis systems include the AUTOPHERESIS C(copyright) Cell Separator and the AMICUS(copyright) Cell Separator, sold by Baxter Healthcare Corporation of Deerfield, Ill. The AUTOPHERESIS C(copyright) utilizes a separator that includes a chamber and rotating membrane. Blood is introduced into the chamber and the membrane separates the blood into (at least) plasma and red blood cells, or other plasma-depleted blood.
The AMICUS(copyright) Cell Separator utilizes a centrifugal separation principle. In the AMICUS(copyright) Separator, whole blood is introduced into a dual-chambered or single-chambered container mounted on a rotatable centrifuge. Whole blood is introduced into the first chamber where red blood cells are separated from platelet-rich plasma (PRP). The PRP flows into a second chamber where it is further separated into platelets and platelet-poor plasma. The disposable fluid circuit of AMICUS(copyright) uses preformed cassettes with flow paths defined therein, which is mounted on the AMICUS(copyright) device. Flow through the flow path is assisted by peristaltic pumps. A more detailed description of the AMICUS(copyright) Separator is provided in U.S. Pat. No. 5,868,696, which is incorporated herein by reference.
Recently, a more, portable automated apheresis system has been developed by Baxter Healthcare Corporation. As described in U.S. Pat. No. 6,325,775, entitled xe2x80x9cSelf-Contained Transportable Blood Processing Device,xe2x80x9d which is incorporated herein by reference, the portable apheresis system is also based on the principle of centrifugal separation. It includes a re-usable hardware module and a disposable fluid circuit. The fluid circuit includes a cassette with pre-formed flow paths, valving stations and pumping stations.
Other manufacturers such as Gambro BCT, Haemonetics, Dideco and Fresenius also provide automated apheresis systems based on centrifugal or other separation principles.
While efforts continue to develop and provide more efficient, economical and easy-to-use apheresis systems, concerns about the availability and safety of the blood supply, as well as an increased understanding of the role of certain blood components and blood related diseases, have led to the development of additional blood related procedures. These additional procedures often include treatment of the blood component so as to provide a safer or more viable component. Some of the additional procedures may involve eradication or removal of undesired compounds or other substances from blood. Some of these additional procedures may involve replacement of a component with another solution. In any case, these procedures often involve many manual steps, several different pieces of equipment or complex fluid circuits. Thus, there exists a need for an automated system that, in addition to separating blood into its components, can carry out one or more other procedures involving the separated components and/or the treatment thereof.
Thus, it would be desirable to provide an automated system that can perform additional procedures using a single piece of re-usable hardware and an easy-to-load, easy-to-use disposable that eliminates the need for many tubing connections and complex routing of tubing. It would also be desirable to provide a single system that does not require regular operator intervention to perform the selected separation and other treatment or processing steps. It would also be desirable to provide a system where all desired separation and processing steps are performed within a single integrated system, and xe2x80x9coff-linexe2x80x9d treatment using separate devices is not required. It would also be desirable to provide a system that can perform multiple fluid separation, processing and/or treatment steps through automated control of flow through the fluid circuit.
One application where automated separating and processing of blood may be desirable is in the automated pre-surgical donation of blood and administration of a replacement fluid such as a blood substitute and/or oxygen carrier. A manual version of this process is described in U.S. Pat. No. 5,865,784, incorporated herein by reference.
Another application where automated separating and processing blood may be desirable is in the salvaging of red blood cells during surgery on a patient. In cell salvage, blood from a wound area or from the body cavity (i.e., extra-vascular or xe2x80x9cshedxe2x80x9d blood) that would otherwise be lost, is collected, processed (or cleaned), and the cleaned blood is returned to the donor. Examples of systems and apparatus used for cell salvage are described in U.S. Pat. No. 5,976,388, which is incorporated herein by reference.
Another application where separating and processing blood may be desirable is in the removal of unwanted substances from blood or a separated blood component such as plasma. For example, the role of cholesterol and low density lipids (LDL) in cardiovascular disease has been well documented. Methods for lipid removal from the plasma of a patient have been developed and are disclosed in U.S. Pat. Nos. 4,895,558, 5,744,038 and 5,911,698, which are incorporated herein by reference.
Still another application where separating and processing blood may be desirable is in the treatment of blood cells. In a particular application, it may be desirable to treat separated red blood cells with enzymes to, for example, convert Type A, B and AB blood cells to the universally acceptable Type O blood cells. Examples of such methods are described in U.S. Pat. Nos. 6,175,420 and 5,671,135, which are incorporated by reference herein.
As described below, there may be additional applications where it may be desired to separate blood into its components for further treatment and/or processing.
Thus, it would be desirable to provide a single system that, in addition to having the ability of withdrawing whole blood and separating it into two or more components, is programmed for, adaptable for, and capable of carrying out at least two or more applications.
In one aspect, the present invention is directed to an automated system for withdrawing and replacing fluids in a surgical patient. The automated system includes a means for separating whole blood into at least two components. The automated system also includes means for withdrawing whole blood from a patient and introducing the whole blood into the means for separating and means in fluid communication with the separation means for collecting a selected amount of one of the components. The component collected may have a known and specific biological function. The system, therefore, may also include means for determining an effective amount of a replacement fluid to be administered to the patient, which may be based at least in part on the amount of the collected component or on other patient data. The automated system of the present invention may also include means for infusing the replacement fluid into the patient.
In a more specific aspect, the automated system of the present invention may include a rotatable centrifuge as the means for separating, and the means for withdrawing may include a plastic tubing set, the tubing defining a flow path between the patient and the separator.
In another aspect, the automated system of the present invention includes means for determining an effective amount of a second replacement fluid and means for infusing the amount of the second replacement fluid into the patient, wherein the amount is based, at least in part, the amount of the component collected or other patient data. The replacement fluid is capable of at least partially providing the biological function of the fraction removed.
In another aspect, the present invention is directed to a method for withdrawing and replacing fluid from a patient. The method includes withdrawing whole blood from a patient and separating the whole blood into at least two components. The method further includes collecting one component that has at least one known biological function, while returning a second component to the patient. The method of the present invention may also include infusing an effective amount of a first replacement fluid to the patient wherein the effective amount is based, at least in part, on the amount of the collected fraction or on other patient data.
In accordance with another, more specific aspect of the present invention, the method may include determining the amount of the collected component by collecting the fraction in a container and weighing the same. Alternatively, determining the amount of the collected component may be achieved by an algorithm that relies on other parameters such as known tubing diameters and pump speeds to calculate the amount of the collected fraction.
In accordance with another aspect of the present invention, the method may include collecting concentrated red blood cells in a container and determining the weight of the red blood cells. The method may further include automatically determining the effective amount of a first replacement fluid based on the weight of the collected red blood cells and automatically infusing the required amount of the first replacement fluid into the patient.